Temperature control



Jan. 22, 1 935.

Filed Jan. 15, 1931 INVENTORS M 3 TTORNEYJ Patented Jan. 22, 1935 PATENTOFFICE 1,988,495 TEMPERATURE CONTROL George E. Hulse and John D.Strobell, New Haven, Conn., assignors to The Safety Car Heating &Lighting Company, a corporation of New Jersey Application January 15,

31 Claims.

This invention relates to temperature control. This invention relates toa method and an apparatus for controlling the temperature of theatmosphere in a space, such as a room, railway car, or the like. I

One of the objects of this invention is to provide anatmosphere-conditioning apparatus of simple design, durable constructionand reliable action. Another object of this invention is to provide anapparatus and system of the abovementioned character which will behighly efficient and well adapted to meet the peculiar andwidely-varying.conditions and requirements met with in practice. Anotherobject of this invention is to provide a system and apparatus of theabove-mentioned character which will be of ready and economicalconstruction, character ized by ease of installation, and capable ofdependable and long-continued operation. An-

- invention is to provide a system and apparatus of the above naturewhich will be automatic in action and may be operated by unskilledpersonnel. Other objects will be in part obvious and in part pointed outhereinafter.

The invention accordingly consists in the features of construction;combinations of elements, arrangements of parts and in the several stepsand relation and order of each of the same to one or more of the others,all as will be illustratively described herein, and the scope of theapplication of which will be indicated in the following claims.

The single figure in the accompanying drawing is a diagrammaticrepresentation showing one of various possible embodiments of themechanical and electrical features of our invention.

As conducive to a clearer ,understanding of certain features of ourinvention, it might at this point be noted that one of variousdisadvantages inherent in known systems and methods for cooling theinterior of a room in hot weather resides in the fact thatgreatdiscomfort is caused because of the oftentimes too great a diiference intemperature between the outside atmosphere, to which the person hasbecome temporarily accustomed, and the temperature inside the cooledroom; the higher that the outside temperature is, the greater is theabove-mentioned difference in temperature, the greater is the rethisinvention thereto.

1931, Serial No. 508,835

sultant discomfort, and the greater are the dimculties in acclimatingones self to the lower temperature. Though the lower or insidetemperature may be one that is well suited to comfort, yet the abruptchange due to entering the cooled space is suflicient to cause chills,and like great discomforts. One of the dominant aims of this inventionis to provide a system and method for avoiding such difliculties anddisadvantages as have just been mentioned.

Turning now to the illustrative embodiment of this invention shown inthe accompanying drawing, a conduit, generally indicated at 10, is sopositioned in relation to the space, such as a room, railway car, or thelike, the temperature of which is to be controlled, that various outlets11 therefrom afiord the discharge of suitable quantities of air into thespace, the latter being diagrammatically indicated at 9. The mouth 12 ofconduit 10 is disposed in such a position that it will receive fresh airfrom a suitable source, such as the outside atmosphere. Adjacent mouth12 is a motor 13, supported in any suitable manner, and driven from theshaft of motor 13 is a fan 15 of suitable size to force the desiredquantity of air through conduit 10, in a direction indicated by arrows,and into the room or space 9. The motor 13 is connected by conductors 16to the main lines 17, which, through a manually operated switch 19, leadto a suitable source of current. Certain advantages of our invention aremore fully realized in connection with the control of temperature in,particularly, passenger vehicles, such as railroad cars, but it is to beunderstood that we do not limit the scope of If this apparatus wereinstalled in a railroad car, the source of current connected to mainlines 17 preferably takes the form of a generator 18 driven from the caraxle and a storage battery 20, an automatic switch 18, of any suitableconstruction, connecting the generator to the battery 20 when itsvoltage is adequate and effecting disconnection when the generatorvoltage drops below a certain value;

in the latter case, the battery 20 serves to supply energy to lines 17and associated'devices. In so far as the broader aspects of ourinvention are concerned, line conductors 17 lead to'any appropriatesource of current.

Positioned in the path of movement of air moved by the fan 15, andconveniently near the mouth 12 of the conduit 10, is a heater,preferably in the form of a coil 21 of pipe adapted to have steam passedtherethrough. A pipe 22 leads from the coil 21, through an electricallyating coil 25, supplied with refrigerant from a suitable refrigerationapparatus to be more fully described hereinafter. When the fan 15 is inmotion, a continuous blast of air is passed over the coils 21 and 25,into the conduit 10, and thence into the space 9, through the outlets11. Furthermore, if steam is passing through heater coil 21, the air isheated, thus heating the space 9, and, conversely, if the refrigerationcoil 25 is effective, the air passing thereover is cooled, thus to coolthe space 9. Thus either a heated medium or a cooled medium is passedinto space 9 according to whether the steam coil 21 or the refrigeratingcoil 25 is in operation.

The refrigeration unit for supplying cooling coil 25 with refrigerantincludes a compressor 28 driven by an electric motor 30, throughsuitable driving connections 31. Motor 30 is connected by conductors 32to the lines 17. The refrigeration apparatus may be of any suitable typeor construction but preferably is of the compression-expansion type. Apipe 3'7 leads compressed refrigerant to a condenser 38, where it iscondensed, whence a pipe 29 conducts the liquefied refrigerant to areceiver or collecting tank 39. A pipe 33 conducts condensed refrigerantfrom the storage tank 39 to refrigerating coil 25 through the expansionvalve 2'7; and a pipe- 26 returns expanded refrigerant from coil 25 tothe compressor, 28.

Heat may be extracted from the refrigerant in the condenser 38 by anysuitable means, and illustratively we have shown condenser 38 aswater-cooled, conveniently by means employing the same cooling waterover and over. In order to keep cooling water supplied tocondenser-cooling coil 41 at a suitable low temperature, we provide acoolingtower including a tank 40 into which the warmed water from thecooling coil 41 in condenser 38 is lead by pipe 43 and through aspraying device 42 in the upper part of tank 40. A fan 44, driven bymotor 45, is disposed at one side of tank 40 to blow suflicient coolingair, in countercurrent relation to the water spray 53' to effect thenecessary cooling. Motor 45 is connected by conductors 46 to the mainlines 1'7. A pipe 47 leads from the bottom-of tank 40 to a rotary pump48 of any desired construction, the pump discharging water, by a pipe49, into the cooling coil 41 in the condenser 38. A motor 50 drives therotary pump 48 and is connected to the main lines 1'7.

Tank 40 is preferably of a size suflicient to hold such a quantity ofwater 52 as to compensate for loss by evaporation over substantialperiods of time. I

It may be further pointed out that the motor 30 for driving thecompressor 28, the motor 45 for actuating the fan 44, and the motor 50for driving the rotary pump 48 are all connected in parallel to mainlines 1'7 but on the same side of an automatic switch 34. Thus whenswitch 34 is closed these three motors will be operated simultaneously.

A thermostatic bulb 54, having therein any suitable medium such as avolatile liquid whose vapor pressure changes in response to temperaturechanges, is positioned inside the space or room 9 whose temperature isto be-regulated. Connected to bulb 54 by a pipe or conduit 55 is apressure-responsive bellows 56, constructed in any suitable manner sothat an increase or decrease of pressure due to the medium disposedtherein and in the bulb 54 will cause an expansion or contraction ofbellows 56 with a consef uent transverse motion of the unanchored orright-hand end of bellows 56. Secured to the right-hand end of bellowsis an am 5'7 pivotally connected at 59 to an arm 58. Arm 58 is pivotedat 60 so that it will swing under the action of bellows 56; at its upperend it carries insulated contacts 61 and 62 for coaction with relativelyfixed contac 63 and 64 respectively, according to the position of arm58. Thus a transverse motion of rod 5'7 connected to the thermostaticbellows 56 is efective to move the contact 61 into engagement with thecontact 63 or to move the contact 62 into engagement with and over thecontact 64.

Contact 63 is movable, however, and is supported by and insulated from aswinging arm 65 pivoted at 66. To one side of arm 65 is a stationarystop 67 limiting the extreme swinging movement of the arm 65 in aclockwise direction. A spring 68 is disposed in such a position as toexert pressure on the arm 65, tending to swing and hold it against thestop 6'7. Thus the swinging arm 65 and the contact '63 carried therebyare prevented from swinging in a clockwise direction beyond the stop 67but if a pressure greater than that of the spring 68 is applied to arm65 on the same side as the stop 6'7, the arm 65 and the contact 63 aremoved in a counterclockwise direction and contact 63 is thus positioneda greater distance toward the right from the contact 64. Contact 64 isof such a length that when the bellows 56 is actuated by a pressurecorresponding to any temperature greater than, for example, 68 F.contact 62 on arm 58 is moved out of engagement therewith. Contact 63 inits normalposition with arm 65 against the stop 6'7, is engaged by thecontact 61 on arm 58 when bellows 56 is afiected by a temperature of,for example, 70 F. or above, The circuits controlled or affected bythese various contacts will be more fully described hereinafter.

A thermostatic bulb "72, similar in construction to the above describedthermostatic bulb 54, is disposed out-doors or 'outside of the space 9whose temperature is to be regulated, and connected thereto by a pipe'73 is a thermostatic bellows '74 like the bellows 56, actuated bychanges in pressure therein due to temperature changes affecting bulb'72.- An arm '75 pivoted at '76, is pivotally connected as at '77 to anarm '78 attached to the free or unanchored end portion of the bellows'74. Ann '75 carries at its upper end an insulated contact '79 adaptedto coact with relatively fixed spaced contacts and 81; as arm '75 ismoved by bellows '74, the contact '79 comes into engagement with eitherthe contact 80 or the contact 81 according to the position of the movingend of the bellows. Contact 81 is here positioned so that when thethermostatic bellows '74 is affected by a pressure corresponding to, forexample, a temperature of 68 F. or below affecting bulb '72, contact '79is moved into engagement therewith, and the contact 80 is herepositioned so that the contact '79 is moved into engagement with it whenthe bellows '74 is actuated by a pressure .parts 87 and 88, one

slotted as at 87 temperature of 73 F. or greater. v

Secured to and movable by arm 75 and related so that its end 85 canengage the swinging arm 65 is an arm member generally indicated at 86.Member 86 is preferably adjustable in length and conveniently consistsof two overlapping of them, part 87, being to receive clamping screws 89and 90. Thus arm members 86 may be made any desired length and the pointat which it engages and begins to move arm 65, which carries contact 63,may be predetermined. Hence, the distance between the contacts 63 and64, de-

pendent upon the action of the member 86, may

be predetermined by the length at which this .a certain predeterminablevalue.

member is set. Likewise, the point or points at which movable contact61, controlled by the inside thermostatic bulb 54, coacts with contact63 may be affected.

The automatic switch 34is, as above noted, positioned in circuit 17-17so that it controls the actuation of motors 30, 45 and 50. Switch 34 iscontrolled by a coil 71 which, when energized, closes switch 34 toeffect operaticn of these motors and the parts operated thereby, andwhich, when de-energized, efiects opening of the switch 34 to stop thesemotors. Coil 71 and the electromagnetic operation of steamline valve ,23are controlled by the contacts above described.

Contacts 64, 81 and are mounted in any suitable manner to be manuallyadjustable, in the directions of the arrows shown in the drawing, andpreferably each of these contacts is provided withan index or, pointermember for coaction with suitable temperature indicia 'or scalessubstantially as shown in the drawing. By such means as these, theseadjustable contacts may be accurately set at willto cause the apparatusto act tomeet the various conditions met with in practice, certainillustrative examples of which may now be considered.

We have hereinabove pointed out certain disadvantages and difiicultiesmet with in achieving the cooling of, for example, the interior of aroom, and as illustrative of one of various features of our inventionwhereby such disadvantages and difficulties are overcome, we may at thispoint note that we make it possible to avoid discomfitting and undesireddifferences in temperature by maintaining a relatively fixed butvariable difference between the outside temperature and the insidetemperature though the former may vary through wide ranges above Forpurposes of illustration, let it be assumed that it is desired tomaintain, in accordance with certain features of our invention, adifference of 5 F. between the outside temperature and the temperaturewithin the space 9, and that, for the and that, therefore, thetemperature desired to be maintained within the space 9 is 70. Let italso be assumed that the temperature within the space 9 is now 73 andduced below 68 F. 4

We first set'contact 81 at the 68 position so that movable contact 79.engages or disengages contact 81 when the outside thermostatic bulb 72is affected by a temperature of 68; we similarly set contact 64 at the68 position so that contact 62 engages'or disengages contact 64 when theinside thermostatic bulb 54 is affected by a temperature within thespace '9 of 68.

is at no time to be re- Movable contact 80 is set at a 70 position, afew degrees higher than the setting of contact 81, so that contact 79 onarm 75 engages or disengages contact 80 when outside thermostatic bulb72 is affected by a temperature of 70.

Arms 75 and 58, under the above assumed conditions, hence occupypositions substantially as shown in the drawing. The adjustment of thelength of extension 86 and the consequent pcsition of contact 63 arethen so fixed that the arc of travel (toward the .left) of contact 61along contact 63 necessary to disengage contact 61 from contact 63corresponds to a 5 temperature arc of travel of arm 58 and contact 61.Further, with the above assumed temperature values, it will be notedthat cooling of the space 9 is now in order, the temperature having tobe brought down to 70 F., 5 lower than the outside temperature of 75 F.

The switch 19 is then closed to make eifective the source of current,either generator 18 or battery 20 or'both. The closing of the switch 19conditions the system for continuous auto matic operation, and the motor13, connected by lines 16 to lines 17, is set in operation and actuatesthe fan 15; it will be noted that motor 13 is connected on the generatorside of automatic switch 34. Thus, a continuous current of air flowsthrough the conduit 10 and out through the various outlets 11 into thespace 9 to accomplish a thorough and constant movement of air in thespace whose temperature is to be regulated. As the temperature in'thisspace, above assumed to be 73 F., is 3 above that preferred,refrigeration or cooling is in the coils 25 in order to cool the airbeing D passed into space 9. As the outside temperature v as shown inthe drawing. Furthermore, as the temperature inside is 73, the arm 58and thus the contact 61 are moved by the thermostatic bellows 56 to aposition in which the contact 61 is in engagement with the contact 63.

With the parts in this position, a circuit is established between thesource of current and the solenoid 71, this circuit extending from oneof lines 17, line 83, contact 79, contact 80, line 84, contact 61,contact 63, line 70, solenoid winding 71, and from the latter, to theother line 17; solenoid 71 being energized, switch 34 closes. Closure ofswitch 34 starts motor 30, motor 45, and motor 50. The moving parts ofthe refrigeration unit are thus actuated and refrigeration takes placein the coil 25; the current of air being passed into thermal contactwith these coils by the fan 15 becomes cooled thereby. This current ofair passes out through the outlets 11 and, circulating in the space 9,cools that space. ,As the temperature inside space 9 is thus reduced,bellows 56 contracts, moving arm 58 and contact 61 toward the left. Whena temperature of 70 in sp 3e 9 has been reached, the thermostaticbellows 56 moves the contact 61 out of engagement with contact 63, thusbreaking the circuit made to take place temperature rises to 78, and, asdescribed above, a fixed difference between the outside and insidetemperatures of 5 is to be maintained; hence the inside temperature mustnow be maintained at 73. The thermostatic bellows '14, being affected bythis increase in temperature under the action of bulb '72, moves arm '75and contact 79 farther along the contact 80, the two remaining inengagement with each other. However, when this action takes place, theextendable member 86 is similarly moved (tothe right) and, being inengagement with the swinging arm 65, thus moves th'e'contact 63 fartherto the right throughout a distance corresponding to the increment ofincrease in outside temperature. The parts in this new position preventcontact 61 from engaging contact 63 until a temperature of about 73inside of space 9 has been reached. Thus no refrigeration in the coil 25and consequently no cooling will take place until a temperature of 73 inspace 9 is exceeded. If such a temperature is reached, the contact 61engages the contact 63, thus completing the circuit to the solenoid 71and the refrigerating parts will function as described above, contact 61disengaging contact 63 when the temperatur of 73 in space 9 is restored.

For further purposes of illustration let it be assumed that it is a veryhot day, and the outside temperature is 90 F. In'such'a case it might bedesirable to have a greater diiference between the temperature insidethe space and the temperature outside the space in order to maintain acomfortable .temperature therein. To increase the temperature differenceto be maintained, screws 89 and 90 are loosened and member 86 isshortened so that contact 61 engages or disengages contact 63 at a pointthat is 10 temperature degrees displaced from the particular point atwhich arm '75 and contact '79 happen to be. Arm 75 assumes a 90position, being moved toward the right of the position it has as shownin the drawing, and arm 65 with contact 63 likewise assumes a positionconsiderably to the right of that shown in the drawing. Under theseconditions, contact 61 will not engage contact 63 until aninside'temperature of about 80 is reached; thus the parts function asdescribed above, maintaining a 10 "difference between the outside andinside temperatures.

Let it now be assumed that the outside temperature falls below 68 F.,and that instead of refrigerating the air supplied to the space 9, it isnow necessary to heat it in order to maintain a comfortable temperaturetherein. When the temperature outside of space 9 is 68, or below, thethermostatic bellows 74 is actuated to move contact 79 into engagementwith contact 81. As arm 75 with extendable member 86 moves to the left,spring 68 causes arm 65 to follow this movement until arm 65 engagesstop 67 so that a subsequent movement of arm 58 to the left is effectiveto move contact 61 out of engagement with contact 63. If the temperatureinside the space 9 falls below 68 F., the inside thermostatic b'ellows56 moves the contact 62 into engagement with the contact 64. A circuitis now established between the source of current and the winding of theelectrically actuated valve 23, this circuit extending from one of thelines 17, line 91, winding of valve 23, line 69, contact 64, contact 62,line 82, contact 81, contact 79, line 83, and to the other of themainlines 17. Valve 23 is thus caused to open and permit steam to passthrough the pipe 22 to the series of heater pipes 21 positioned in frontof the fan 15. The current of air passing into thermal contact withpipes '21 is heated and is then passed through the conduit 10 and theoutlets 11 to circulate in and heat the space 9. This heating actioncontinues until the temperature in the space rises above 68, when thethermostatic bellows 56 moves the contact 62 out of engagement withcontact 64, thus breaking the circuit between the valve 23 and thesource of current. The valve 23 closes, stopping the circulation ofsteam through the series of pipes 21 and heating of the incoming airceases.

A subsequent decrease in the temperature inside of space 9 effects amovement of arm 58 and contact 62 toward the left to re-establish thecircuit of the electro-magnetic means operating the valve 23, whence theheating operation continues until the desired inside temperature isre-established. This cycle or these cycles of heating operations arerepeated under the control of the inside thermostatic bulb 54, as longas the temperature outside of the space 9 is at or below 68 F., asdetermined by the position "of adjustable contact 81' with which contact'79,

controlled by the outside thermostatic bulb 72, coacts. Should it bedesired to prevent lowering of the inside temperature below atemperature other than the above-assumed 68 F., ad-

justable contacts 64 and 81 are correspondingly reset. Also, it may bedesired to prevent heating action inside of the space 9 as long as thetemperature outside of the space 9 is at or above a temperature otherthan the above-assumed 68 F.; in that case, contact 81 iscorrespondingly reset.

It will thus be seen that there has been provided in this invention asystem and apparatus in which the various objects hereinbefore noted,together with many thoroughly practical advantages, are successfullyachieved. It will be seen that the apparatus is of thoroughly dependableaction and is, moreover, well adapted to meet a great variety ofpossible practical conditions met with in practice, of which the purelyillustrative examples above-described in detail are but a few. Theflexibility of control or setting of the system and apparatus is suchthat not only may the temperature difierence desired to be maintainedbetween the outside temperature and the inside temperature be widelyvaried, but also the limiting temperatures affecting the initiation ofheating action or cooling action inside of space 9 may be set throughoutwide ranges.

a As many possible embodiments may be made in this invention, and asmany steps may be made in the embodiments above set forth or in thesteps hereinbefore set forth, it is to be understood that all matterhereinbefore described or set forth in the accompanying drawing is to beinterpreted as illustrative and not in a limiting sense.

We claim:

1. In apparatus of the character described, in combination, meansforming a space whose temperature is to be regulated, a refrigerationunit for said space, a controlling system for said refrigeration unitcomprising thermostatic apparatus responsive to the temperature insidesaid space, thermostatic apparatus responsive to the temperature outsidesaid space, said two apparatuses adapted to place said refrigerationunit in operation when the parts of said two apparatuses are in certainpositions, said secondmentioned thermostatic apparatus adapted to changethe position of one of the parts of said first-mentioned apparatus tochange the controlling standard of said controlling system.

2. In apparatus of the character described, in

combination, means forming a space whose temperature is to be regulated,a refrigeration unit for said space, a heating unit for said space,thermostatic means responsive to the temperature inside said space forselectively controlling the operation of said refrigeration unit andsaid heating unit, and thermostatic means responsive to the temperatureoutside said space adapted to coact with said first-mentionedthermostatic means to control the operation of said heating unit andsaid refrigeration unit, said second-mentioned thermostatic meansadapted to modify the action of said first-mentioned thermostatic meanswhereby said first-mentioned'thermostatic means operates for temperaturevalues determined by said second-mentioned thermostatic means.

3. In apparatus of the character described, in combination, meansforming a space whose temperature is to be regulated, a refrigerationunit for sai'dspace, a heating unit for said space, thermostatic meansresponsive to the temperature inside said space including a plurality ofparts adapted to engage or disengage, and thermostatic means outsidesaid space including a plurality of parts adapted to engage ordisengage, said refrigeration unit adapted to operate when-the parts ofsaid first-mentioned thermostatic means are in engagement with eachother and the parts of said second-mentioned thermostatic means are inengagement with each other, said second-mentioned thermostatic meansadapted to move one of said parts of said first-mentioned thermostaticmeans with respect to the other parts of said first-mentionedthermostatic means to change the engaging position of the parts of saidfirst-mentioned thermostatic means. 1

4. In apparatus of the character described, in combination, meansforming a space whose temperature is to be regulated, a refrigerationunit for said space, an electric motor for driving an element of saidrefrigeration unit, a source of current, a-circuit between said sourceof current and said motor, a controlling system for said circuitincluding a switch having two movable contacts, a thermostatic deviceresponsive to the temperature inside said space for controlling theposition of one of said movable contacts, a switch including a movablecontact and arelatively fixed contact, a thermostatic device forcontrolling the position of said last-mentioned movable contact withrespect to said fixed contact, and means forming an operative connectionbetween said last-mentioned thermostatic device and the other of saidmovable contacts of said firstmentioned switch whereby the operation ofsaid last-mentioned thermostatic device controls the position of saidlast-mentioned movable contact with respect to said first-mentionedmovable contact.

5. In apparatus of the character described, in

combination, means forming a space whose tem-- perature is to beregulated, a refrigeration unit for said space, a switch responsive tothe temperature outside said space, and a switch responsive to thetemperature inside said space, said first-mentioned switch adapted tomodify the action of said second-mentioned switch whereby apredetermined fixed difference in temperature between the inside of saidspace and the outside of said space is maintained.

6. In apparatus of the character described, in combination, meansforming a space whose temperature is to be regulated, a refrigerationunit for said space, said unit including a compressor and electric motorfor driving said compressor, a circuit between said electric motor and asource of current, means for breaking and making said circuit,temperature responsive devices inside said space and outside said spacecoacting with each other to control said last-mentioned means, and meansfor fixing the range of coaction of said devices to maintain apredetermined difference between the temperatures within said space andoutside said space.

7. In apparatus of the character described, in combination, a spacewhose temperature is to be regulated, a refrigeration unit for saidspace including a compressor and a condenser, means for passing coolingwater through said condenser, means for cooling said water including anelectric fan, an electric motor for actuating said compressor, a circuitbetween a source of current and said motor and said fan, means formaking and breaking said circuit, and temperature responsive deviceslocated inside said space and outside said space coacting to controlsaid last-mentioned means to maintain a predetermined fixed differencebetween the temperatures outside said space and inside said space as theoutside temperature varies.

8. In apparatus of the character described, in combination, a spacewhose temperature is to be regulated, a refrigeration'unit for saidspace ineluding a compressor and a condenser, means for passing coolingwater through said condenser, means for cooling said water including anelectric fan, an electric motor for actuating said compressor, a circuitincluding a source of current and said motor and said fan, means formaking and breaking said circuit, temperature responsive means forcontrolling said last-mentioned means to maintain a difference betweenthe temperatures outside said space and inside said space as the outsidetemperature varies, and means for breaking said circuit when the outsidetemperature reaches a certain minimum value.

9. In apparatus of the character described, in combination, a spacewhose temperature is to be regulated, an electric circuit, arefrigeration unit for said space dependent for operation upon thecondition of said circuit, a switch in said circuit, electric means foractuating said switch, a switch in the circuit of said electric means, athermostatic member responsive to the temperature inside said space foractuating said secondmentioned switch when the temperature inside saidspace is at or above a certain value, a switch in the circuit of saidelectric means, a thermostatic member responsive to the temperatureoutside of said space and adapted to actuate said last-mentioned switchwhen the temperature outside said space reaches a certain value, saidsecond-mentioned value being greater than said first-mentioned value.

10. In apparatus of the character described, in combination, a spacewhose temperature is to be regulated, a refrigeration unit for saidspace, electrical means for operating said refrigeration unit, a sourceof current, a circuit between said source-of current and said electricalmeans, a switch in said circuit, electric means for actuating saidswitch, a switch having two contacts in the circuit of said electricmeans, thermostatic means responsive to the temperature inside saidspace for moving one of said contacts into engagement with the other ofsaid contacts when the temperature of said space reaches a certainvalue, a second switch in the circuit of said electric means, and meansresponsive to the. temperature outside said space for closing saidlastmentioned switch when the temperature outside said space reaches orexceeds a certain value, saidlast-mentioned means adapted tochange theposition of one of said contacts with respect to the other of saidcontacts so that said secondmentioned switch closes at a differenttemperature value in said space.

11. In apparatus of the character described, in combination, meansforming a space whose temperature is to be regulated, a refrigerationunit for said space, electrical means for driving an element of saidrefrigeration unit, a source of current, a circuit between saidelectrical means and said source of current, switching means forcontrolling said circuit including a movable contact, a thermostatresponsive to the temperature inside said space for controlling therange of movement of said contact, a second movable contact, and athermostatic device responsive to the temperature outside said spaceforcontrolling the movement of said last-mentioned contact relative tosaid first-mentioned contact whereby both of said thermostatic devices'coact to maintain a predetermined fixed difference betweenthetemperature inside said space and the temperature outside said space.

12,111 apparatus of the character described, in combination, meansforming a space whose temperature is to be regulated, a refrigerationunit for said space, electrical means for driving an element of saidrefrigeration unit, a source of 40 current, a circuit between saidelectrical means and said source of current, switching means forcontrolling said circuit including a first contact,

a second contact, a thermostatic device responsive to the temperatureinside said space for 45 controlling the engagement and disengagement ofsaid second contact with said first contact, a

third contact, a fourth contact, and a thermostatic device responsive tothe temperature outside said space for controlling the engagement 50 anddisengagement of said fourth'contact with said third contact, saidlast-mentioned thermostatic device adapted to control the position ofsaid first contact with respect to said second contact whereby saidcircuit is closed when said first 55 and second contacts engage and saidthird and fourth contacts engage.

13. In apparatus of the character described, in combination, meansforming a space whose temperature is to be regulated, a refrigeration 60unit for said space, temperature responsive means inside said space forcontrolling the operation of said refrigeration unit, temperatureresponsive means outside said space for controlling the operation ofsaid refrigeration unit,

65 said means coacting to maintain a predetermined difference betweenthe temperatures inside and outside said space, and means related tosaid last-mentioned temperature responsive means for changing at willthe operative range 0 of said first-mentioned temperature responsivemeans.

14. In apparatus of the character described, in combination, meansforming a space whose temperature is to be regulated, an electric cir-75 cuit, a refrigeration unit for said space dependcut for actuationupon the condition of said circuit, a switch for controlling saidcircuit comprising a relatively fixed contact and a movable contact,means responsive to the temperature in said space adapted to move saidmovable con- 5 tact into engagement with said fixed contact when thetemperature of said space reaches a certain value, a second switch forcontrolling said circuit comprising a relatively fixed contact and arelatively movable contact, thermostatic means outside said space formoving said last-mentioned movable contact into engage-. ment with saidlast-mentioned fixed contact when the temperature outside said spacereaches a certain value, and means associated with said last-mentionedmovable contact adapted to move said first-mentioned relatively fixedcontact in the direction of movement of said first-mentioned movablecontact when the temperature outside said space is at or above a certainvalue.

15. In apparatus of the character described, in combination, meansforming a space whose temperature is to be regulated, a refrigerationunit including a cooling coil, a heating coil, means for forcing airpast said coils and into said space, and temperature responsive devicesinside said space and outside said space for controlling the operationof said refrigeration unit and said heating coil, said temperatureresponsive devices coacting to maintain a predetermined differencebetween the temperature inside said space and outside said space whensaid temperatures are above certain values and for maintaining a fixedtemperature in said space when the temperature outside said space isbelow a certain value.

16. In apparatus ofthe character described, in combination, means forpassing a medium into thermal relation to a space whose temperature isto be regulated, refrigeration means for cooling said medium, heatingmeans for heating said medium, means thermally responsive to thetemperature within said space for selectively controlling the action ofsaid heating means and said refrigeration unit, and temperature-responsive means outside said space coacting with said last-mentionedmeans to maintain a fixed difference between the temperatures outsidesaid space and inside said space when said temperatures are abovecertain limits.

17. In apparatus of the character described, in combination, means forpassing a medium into thermal relation to a space whose temperature isto be regulated, refrigeration means for cooling said medium, heatingmeans for heating said medium, means thermally responsive to thetemperature within said space for selectively controlling the action ofsaid heating means and said refrigeration unitfind tempera-' tureresponsive means outside said space coacting with saidlast-mentionedmeans to maintain a fixed diiference between thetemperatures outside said space and inside said space when saidtemperatures are above certain limits and for causing action of saidheating means when the temperature of said space falls below a certainlimit.

18. In apparatus of the character described, in combination, meansforming a space whose temperature is to be regulated, a refrigerationunit for said space, means for controlling the action of said unit,means responsive to the temperature outside said space and to thetemperature inside said space for affecting said controlling means tocause said refrigeration 75 unit to maintain a predetermined fixeddifference between the outside and inside temperatures, heating meansfor said space, and means effective, when a receding outside temperaturecauses said temperature responsive means to efiect depression of theinside temperature to a certain minimum, to halt the action of saidreirigeration unit and initiate action of said heating unit.

- 19. In apparatus of the character described, in combination, meansforming a space whose temperature is to be controlled, means for coolingsaid space, a switch responsive to temperature outside of said space, aswitch responsive to temperature inside of said space and having acontact controlled in its position by said firstmentioned switch, andelectrical control means for said cooling means controlled by saidswitches.

20. In apparatus of the character described, in combination, meansforming a space whose temperature is to be controlled, means for coolingsaid space, a switch responsive to temperature outside of said space, aswitch responsive to temperature inside of said space and having acontact controlled in its positionv by said firstmentioned switch,electrical control means for said cooling means controlled by saidswitches,

and means limiting the position of said contact ing said space, a switchresponsive to tempera-.

ture outside of said space, a switch responsive to temperature inside ofsaid space and having a contact controlled in its position by saidfirstmentioned switch, electrical control means for said cooling meanscontrolled 'by saidswitches, heating means for said space, meanslimiting the movement of said contact in response to the operation ofsaid first-mentioned switch to prevent cooling by said cooling meanswhen the temperature inside of said space recedes to a certain value,and means for causing heating of said space by said heating means uponfurther recession in temperature outside of said space.

22. In apparatus of the character described, in combination, meansforming a space whose temperature is to be controlled, means for coolingsaid space, a switch responsive to temperature outside of said space, aswitch responsive to temperature inside of said space and having acontact controlled in its position by said first-mentioned switch,electrical control means for said cooling means controlled by saidswitches, heating means for said space, means limiting the position ofsaid contact to prevent cooling by said cooling means when thetemperature inside of said space recedes to a certain value, and meanscontrolled by both of said thermostatic switches in response torecession in temperatures outside and inside of said space forinitiating the heating action of said heating means.

23. In apparatus or the character described, in combination, meansforming a space whose temperature is to be controlled, means for coolingsaid space, a member variable in position in accordance with changes intemperature outside of said space, a member variable in position inaccordance with changes inside of said space, and control means for saidcooling means dependent upon departures from a certain predeterminedfixed difierence in the positions of said two members.

24. In apparatus of the character described, in combination, meansforming a space whose temperature is to 'be controlled, means forcooling said space, a member variable in position in accordance withchanges in temperature outside of said space, a member variable inposition in accordance with changes inside of said space, heating meansfor said space, control means for said cooling means dependent upondepartures from acertain difference in the positions of said two membersas long as said members occupy positions corresponding to temperaturesabove certain values, and control means for said heating means adaptedto cause the latter to become efiective when said two members occupypositions corresponding to temperatures below said certain values.

25. In apparatus of the character described, in combination, meansforming a space whose temperature is to be controlled, means for coolingsaid space, heating means for said space, a switch member responsive totemperature outside of said space and coacting with two contacts toclose a circuit upon increase in outside temperature and to close acircuit upon decrease in outside temperature, a switch member responsiveto temperature inside of said space and having a movable contact, saidlast-mentioned switch member and said movable contact being connccted insaid first above-mentioned circuit, means causing said movable contactto vary in its position in accordance with changes in temperatureoutside of said space, control means for said cooling means connected insaid first above-mentioned circuit, and control means for said heatingmeans connected in said second above-mentioned circuit.

26. In apparatus of the character described, in combination, meansforming a space whose temperature is to be controlled, means for coolingsaid space, a switch member movable in position in accordance withchanges in temperature inside of said space, a switch member coactingwith,

said first-mentioned switch member and movable in position in accordancewith changes in temperature outside of. said space, and means wherebysaid switch members control the action of said cooling means to maintaina fixed difference between the temperatures inside said space andoutside said space.

27. In apparatus of the general character described, in combination,means forming a space whose temperature is to be regulated, arefrigerating unit;for cooling'said space, thermostatic means responsiveto the temperature outside said space, a thermostatic part responsive tothe dry bulb temperature inside said space, and means adapted to actuatesaid refrigerating unit when said thermostatic means and saidthermostatic part respond to temperatures whose dif- Ierence is greaterthan a certain predetermined fixed value thereby to maintain a fixeddifference between the temperature outside said space and thetemperature inside said space.

28. In apparatus of the general character described, in combination,means forming a space whose temperature is to be regulated, arefrigerating unit for cooling said space, means responsive to the drybulb temperature 01 said space adapted to cause the actuation of saidrefrigerating unit when the dry bulb temperature thereof exceeds acertain predetermined value, and means responsive to the temperatureoutside said space adaptedto act on said lastmentioned means to changesaid temperature value and thus maintain a predetermined fixeddifference between the dry bulb temperature inside said space andoutside said space.

29. In a temperature regulating system, in combination, means forming anair space whose temperature is to be regulated, means for cooling saidspace, dry bulb thermostatic means responsive to the temperature of saidspace for exerting an exclusive control of the efiect of saidlast-mentioned means on said space, and means responsive to thetemperature conditions outdoors for changing the standard of operationof said last-mentioned means to cause higher temperature levels to bemaintained within said space as said outdoor temperature rises and tocause lower temperature levels to be maintained within said space assaid outdoor temperature falls, each temperature level in said spacebeing maintained at a constant during the continuation of any constanttemperature level outdoors.

30. In a temperature regulating system, in combination, means forming anair space whose temperature is to be regulated, means for cooling saidspace, dry bulb thermostatic means responsive to the temperature of saidspace for exerting an exclusive control over the starting and stoppingof said last-mentioned means, and means responsive to the temperatureconditions outdoors for changing the standard of operation of saidlast-mentioned means to cause higher temperature levels to be maintainedwithin said space as said outdoor temperature rises and to cause lowertemperature levels to be maintained within said space as said outdoortemperature falls, each temperature level in said space being maintainedat a constant during the continuation of any constant temperature leveloutdoors.

31. In a temperature regulating system, in combination, means forming anair space whose temperature is to be regulated, means for cooling saidspace, dry bulb thermostatic means responsive to the temperature of saidspace for exerting an exclusive control of the effect of saidlast-mentioned means on said space, and meansresponsive to thetemperature conditions outdoors for changing the standard of opera! tionof said last-mentioned means to cause higher temperature levels to bemaintained within said space as said outdoor temperature rises and tocause lower temperature levels to be maintained within said space assaid outdoor temperature falls, said last-mentioned means only operatingwhen said outdoor temperature rises above a certain predetermined level,each temperature level in said space being maintained at a constantduring the continuation of any constant temperature level outdoors.

GEORGE E. HULSE.

JOHN D. STROBELL.

